Install Pi with bb's own runtime when Node.js is missing

plugins/provider-pi/PLUGIN_OVERVIEW.md

@@ -13,6 +13,6 @@ The plugin starts `pi` in RPC mode on the host and loads a small bb extension in
 
 ## Requirements
 
-- Install the Pi coding agent on the host machine: `npm install -g @earendil-works/pi-coding-agent`. Version 0.84.0 or newer is required.
+- Install the Pi coding agent on the host machine: `npm install -g @earendil-works/pi-coding-agent`. Version 0.84.0 or newer is required. On a machine without npm, Setup's Install puts Pi in bb's own data directory using the Node.js runtime bundled with bb; no admin rights are needed.
 - Sign in with `pi` on that machine.
 - Optional: set `BB_PI_BRIDGE_COMMAND` and `BB_PI_BRIDGE_ARGS` on the host to use a Pi executable that is not on `PATH`.

plugins/provider-pi/README.md

@@ -15,6 +15,10 @@ What lives here:
 - `src/delta-translation.ts` — pi's session events become bb's thread deltas.
 - `src/bridge/provider-maintenance.ts` — the install gate (`pi --version`
   ≥ 0.84.0) and the npm install/update actions.
+- `src/bridge/bundled-runtime.ts` — when the host has no `npm`, Install runs
+  bb's bundled npm on the runtime the bridge runs on (`process.execPath`, in
+  Node mode under Electron) into `<bridge-data>/pi-npm-global`. A `pi` on
+  `PATH` still wins; otherwise that copy launches on the same runtime.
 - `src/bridge/extension-ui.ts` — pi extension dialogs reach the user:
   `ctx.ui.select/confirm/input/editor` inside a pi extension arrive as pi RPC
   `extension_ui_request` lines, the bridge forwards each dialog as a

plugins/provider-pi/src/bridge/bridge.ts

@@ -47,6 +47,10 @@ import {
   type PiSessionParams,
 } from "../session-params.js";
 import { piSessionNeedsRelocation } from "./session-cwd.js";
+import {
+  configurePiBundledRuntime,
+  resolveBundledNpmCliFrom,
+} from "./bundled-runtime.js";
 import { BB_PI_EXTENSION_SOURCE } from "./bb-pi-extension.js";
 import {
   createExtensionUiCoordinator,
@@ -1239,6 +1243,10 @@ export async function experimental_closeAllForTests(): Promise<void> {
 export const experimental_providerBridge = experimental_defineProviderBridge({
   handleLine,
   start: (context) => {
+    configurePiBundledRuntime({
+      dataDir: context.dataDir,
+      npmCli: resolveBundledNpmCliFrom(process.argv[1]),
+    });
     scratchDir = join(context.tempDir, "pi");
     scratchDirIsPrivate = false;
     mkdirSync(scratchDir, { recursive: true });

plugins/provider-pi/src/bridge/bundled-runtime.test.ts

@@ -0,0 +1,79 @@
+import { spawnSync } from "node:child_process";
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import {
+  bundledPiInstallCommand,
+  configurePiBundledRuntime,
+  resetPiBundledRuntimeForTests,
+} from "./bundled-runtime.js";
+
+describe("Pi install on bb's own runtime", () => {
+  let root: string;
+
+  beforeEach(async () => {
+    root = await fs.mkdtemp(path.join(os.tmpdir(), "bb-pi-node-shim-"));
+  });
+
+  afterEach(async () => {
+    resetPiBundledRuntimeForTests();
+    await fs.rm(root, { force: true, recursive: true });
+  });
+
+  it("lets dependency install scripts run `node` when no Node.js is on PATH", async () => {
+    const fakeNpm = path.join(root, "fake-npm-cli.js");
+    await fs.writeFile(
+      fakeNpm,
+      [
+        'const { spawnSync } = require("node:child_process");',
+        'const result = spawnSync("node", ["-e", "process.stdout.write(\'from-node\')"], { shell: process.platform === "win32", encoding: "utf8" });',
+        'process.stdout.write(`status=${result.status} out=${result.stdout ?? ""} argv=${process.argv.slice(2).join(",")}`);',
+      ].join("\n"),
+    );
+    const emptyPath = path.join(root, "empty-path");
+    await fs.mkdir(emptyPath);
+    configurePiBundledRuntime({ dataDir: root, npmCli: fakeNpm });
+
+    const install = bundledPiInstallCommand();
+    expect(install).not.toBeNull();
+    if (install === null) return;
+    const run = spawnSync(install.command, install.args, {
+      encoding: "utf8",
+      env: { ...process.env, PATH: emptyPath, Path: emptyPath },
+    });
+
+    expect(run.stdout).toContain("status=0 out=from-node");
+    expect(run.stdout).toContain("argv=install,--global");
+  });
+
+  it("keeps `node` working when bb's runtime lives under a non-ASCII path with %", async () => {
+    const runtimeDir = path.join(root, "Jösé 100%");
+    await fs.mkdir(runtimeDir);
+    const runtime = path.join(runtimeDir, path.basename(process.execPath));
+    await fs.copyFile(process.execPath, runtime);
+    await fs.chmod(runtime, 0o755);
+    const fakeNpm = path.join(root, "fake-npm-cli.js");
+    await fs.writeFile(
+      fakeNpm,
+      [
+        'const { spawnSync } = require("node:child_process");',
+        'const result = spawnSync("node", ["-e", "process.stdout.write(\'from-node\')"], { shell: process.platform === "win32", encoding: "utf8" });',
+        'process.stdout.write(`status=${result.status} out=${result.stdout ?? ""}`);',
+      ].join("\n"),
+    );
+    const emptyPath = path.join(root, "empty-path");
+    await fs.mkdir(emptyPath);
+    configurePiBundledRuntime({ dataDir: root, npmCli: fakeNpm });
+
+    const install = bundledPiInstallCommand();
+    expect(install).not.toBeNull();
+    if (install === null) return;
+    const run = spawnSync(runtime, install.args, {
+      encoding: "utf8",
+      env: { ...process.env, PATH: emptyPath, Path: emptyPath },
+    });
+
+    expect(run.stdout).toContain("status=0 out=from-node");
+  });
+});

plugins/provider-pi/src/bridge/bundled-runtime.ts

@@ -0,0 +1,176 @@
+import { execFile } from "node:child_process";
+import { readFileSync, statSync } from "node:fs";
+import { createRequire } from "node:module";
+import path from "node:path";
+import { promisify } from "node:util";
+import {
+  type ProviderInstallationCommand,
+  experimental_compareVersions as compareVersions,
+  experimental_formatCommand as formatCommand,
+  experimental_versionFrom as versionFrom,
+} from "@get-bb/plugin-sdk/provider-bridge";
+import { z } from "zod";
+
+const execFileAsync = promisify(execFile);
+const PI_PACKAGE_SEGMENTS = ["@earendil-works", "pi-coding-agent"] as const;
+const PI_PACKAGE_NAME = PI_PACKAGE_SEGMENTS.join("/");
+const PI_MINIMUM_NODE_VERSION = "22.19.0";
+const BUNDLED_PREFIX_DIR_NAME = "pi-npm-global";
+const LATEST_VERSION_TIMEOUT_MS = 15_000;
+const PI_BOOTSTRAP_SOURCE =
+  "delete process.env.ELECTRON_RUN_AS_NODE;import(require('node:url').pathToFileURL(process.argv[1]).href)";
+const NPM_BOOTSTRAP_SOURCE = [
+  "const fs=require('node:fs'),path=require('node:path');",
+  "const [prefix,npmCli,...rest]=process.argv.slice(1);",
+  "const shim=path.join(prefix,'.bb-node-shim');",
+  "fs.mkdirSync(shim,{recursive:true});",
+  "process.env.PI_BB_NODE_RUNTIME=process.execPath;",
+  "if(process.platform==='win32'){fs.writeFileSync(path.join(shim,'node.cmd'),'@echo off\\r\\nsetlocal\\r\\nset \"ELECTRON_RUN_AS_NODE=1\"\\r\\n\"%PI_BB_NODE_RUNTIME%\" %*\\r\\n');}",
+  "else{const f=path.join(shim,'node');fs.writeFileSync(f,'#!/bin/sh\\nELECTRON_RUN_AS_NODE=1 exec \"$PI_BB_NODE_RUNTIME\" \"$@\"\\n');fs.chmodSync(f,0o755);}",
+  "const key=Object.keys(process.env).find(k=>k.toUpperCase()==='PATH')||'PATH';",
+  "process.env[key]=shim+path.delimiter+(process.env[key]||'');",
+  "process.argv=[process.execPath,npmCli,...rest];",
+  "require(npmCli);",
+].join("");
+
+const piPackageSchema = z.object({
+  bin: z.union([z.string().min(1), z.object({ pi: z.string().min(1) })]),
+});
+
+interface PiBundledRuntime {
+  prefix: string;
+  npmCli: string | null;
+}
+
+let bundledRuntime: PiBundledRuntime | null = null;
+
+function isFile(file: string): boolean {
+  try {
+    return statSync(file).isFile();
+  } catch {
+    return false;
+  }
+}
+
+export function resolveBundledNpmCliFrom(
+  entryPath: string | undefined,
+): string | null {
+  if (entryPath === undefined || !path.isAbsolute(entryPath)) return null;
+  try {
+    const npmPackageJson = createRequire(entryPath).resolve("npm/package.json");
+    const cli = path.join(path.dirname(npmPackageJson), "bin", "npm-cli.js");
+    return isFile(cli) ? cli : null;
+  } catch {
+    return null;
+  }
+}
+
+export function configurePiBundledRuntime(args: {
+  dataDir: string;
+  npmCli: string | null;
+}): void {
+  bundledRuntime = {
+    prefix: path.join(args.dataDir, BUNDLED_PREFIX_DIR_NAME),
+    npmCli: args.npmCli,
+  };
+}
+
+export function resetPiBundledRuntimeForTests(): void {
+  bundledRuntime = null;
+}
+
+export function bbRuntimeEnv(env: NodeJS.ProcessEnv): NodeJS.ProcessEnv {
+  return process.versions.electron === undefined
+    ? env
+    : { ...env, ELECTRON_RUN_AS_NODE: "1" };
+}
+
+function bundledPackageDir(prefix: string): string {
+  return process.platform === "win32"
+    ? path.join(prefix, "node_modules", ...PI_PACKAGE_SEGMENTS)
+    : path.join(prefix, "lib", "node_modules", ...PI_PACKAGE_SEGMENTS);
+}
+
+export function resolveBundledPiCli(): string | null {
+  if (bundledRuntime === null) return null;
+  const packageDir = bundledPackageDir(bundledRuntime.prefix);
+  try {
+    const pkg = piPackageSchema.parse(
+      JSON.parse(readFileSync(path.join(packageDir, "package.json"), "utf8")),
+    );
+    const bin = typeof pkg.bin === "string" ? pkg.bin : pkg.bin.pi;
+    const cli = path.resolve(packageDir, bin);
+    const relative = path.relative(packageDir, cli);
+    if (relative.startsWith("..") || path.isAbsolute(relative)) return null;
+    return isFile(cli) ? cli : null;
+  } catch {
+    return null;
+  }
+}
+
+export function bundledPiLaunch(cli: string): {
+  command: string;
+  args: string[];
+} {
+  return {
+    command: process.execPath,
+    args: ["-e", PI_BOOTSTRAP_SOURCE, cli],
+  };
+}
+
+export function isBundledPiLaunch(launch: {
+  command: string;
+  args: string[];
+}): boolean {
+  return (
+    launch.command === process.execPath &&
+    launch.args[0] === "-e" &&
+    launch.args[1] === PI_BOOTSTRAP_SOURCE
+  );
+}
+
+function usableBundledNpm(): { prefix: string; npmCli: string } | null {
+  if (bundledRuntime === null || bundledRuntime.npmCli === null) return null;
+  if (compareVersions(process.versions.node, PI_MINIMUM_NODE_VERSION) < 0) {
+    return null;
+  }
+  return { prefix: bundledRuntime.prefix, npmCli: bundledRuntime.npmCli };
+}
+
+export function bundledPiInstallCommand(): ProviderInstallationCommand | null {
+  const runtime = usableBundledNpm();
+  if (runtime === null) return null;
+  const args = [
+    "-e",
+    NPM_BOOTSTRAP_SOURCE,
+    runtime.prefix,
+    runtime.npmCli,
+    "install",
+    "--global",
+    "--prefix",
+    runtime.prefix,
+    "--no-audit",
+    "--no-fund",
+    `${PI_PACKAGE_NAME}@latest`,
+  ];
+  return {
+    command: process.execPath,
+    args,
+    displayCommand: formatCommand(process.execPath, args),
+  };
+}
+
+export async function bundledPiLatestVersion(): Promise<string | null> {
+  const runtime = usableBundledNpm();
+  if (runtime === null) return null;
+  try {
+    const { stdout } = await execFileAsync(
+      process.execPath,
+      [runtime.npmCli, "view", PI_PACKAGE_NAME, "version"],
+      { env: bbRuntimeEnv(process.env), timeout: LATEST_VERSION_TIMEOUT_MS },
+    );
+    return versionFrom(stdout);
+  } catch {
+    return null;
+  }
+}

plugins/provider-pi/src/bridge/provider-maintenance.bun.test.ts

@@ -30,6 +30,8 @@ vi.mock("@get-bb/plugin-sdk/provider-bridge", async (importOriginal) => {
 });
 
 vi.mock("./rpc-child.js", () => ({
+  piProcessEnv: (_launch: unknown, env: NodeJS.ProcessEnv) => env,
+  resolveBundledPiInUse: () => null,
   resolvePiLaunch: () => ({ command: probeState.executablePath, args: [] }),
   resolvePiProcessLaunch: () => ({
     command: probeState.executablePath,